Per wiki policy, Spoilers Off applies here and all spoilers are unmarked. You Have Been Warned.
- The Honkai in general can be considered nightmare fuel. They're an unstoppable force with the sole purpose of destroying humanity. They can turn normal people into mindless grunts, create sleeper agents out of the Herrschers, they evolve with civilization to keep it in check, and are seemingly endless in numbers. The worst part? They've already succeeded in destroying humanity once, and they're more than ready to do it again.
- Chapter 8, Act 2's ending cutscene teeters between Tear Jerker and nightmare fuel as a pure Mook Horror Show for Anti-Entropy's robot army. Think about it, your best friend is possessed, has nearly strangled you to death, you can't get through to her, and now she's summoning an endless army of Honkai beasts that not even an army of robots can stop. The real kicker is Herrscher of the Void catching an entire artillery barrage and sending it right back at Anti-Entropy's forces, wiping them out in one go while Mei looks on in horror. The most unnerving part is the very last shot of Herrscher of the Void (together with Benares), standing over the destruction... then she glares at the viewer out of the corner of her eye as the cutscene ends.
- Herrscher of the Void herself is this. It's Kiana taken over by her Superpowered Evil Side in the form of Sirin, the original Herrscher of the Void whom Kiana (actually K423, a clone of the original Kiana) was basically created to be the reincarnation body for. She's cold, cruel, vicious and vindictive, and she reaffirms her domination of Kiana's body by using it to bring destruction and suffering. She's especially focused on driving poor Kiana mad with hatred and despair by torturing her loved ones and messing with Kiana's mind using her powers of illusion and judicious use of hateful diatribe. Keep in mind that she nearly succeeded in destroying the world once already, and even after averting that the world still turned into even more of a Crapsack World than it was because of the damage she still did! The first time she was stopped, she killed Kiana's mother Cecilia and scores of Valkyries (including Cecilia's entire team of S-Rank companions!) and nearly killed Siegfried too, and the second time necessitated Himeko's Heroic Sacrifice to stop the rampage and then Fu Hua's to make it just barely stick. Even with Fu Hua's consciousness working full time to help Kiana keep her ego under control, Sirin is still there, very much awake, aware and ready anytime to steal back control of the body should Kiana's emotional state plummet or she overuse her powers; Kiana is a ticking time-bomb who could go off at any moment, releasing the walking disaster that is Sirin upon the world once more.
- Tying directly into the last part of the previous paragraph: The page image is a failure screen from the first level of ch. 10 in the game's Story mode, where Kiana has had the Herrscher of the Void subdued but is still struggling to control it. If you use your Herrscher energy too much in the level, regardless of how far you get, you immediately fail, with the image showing that the Herrscher has succeeded in permanently taking control of Kiana. It's probably the one image in the game that's played for straight horror and is very effective.
- The context inside the Babylon research facility is rather terrifying. It gives you the isolated atmosphere, the poor children (including Sirin) end up here due to being abducted by Schicksal's forces, they get experimented on (with rather gruesome results). In the game itself, when you visit it (or a virtual recreation of it), there are enemies labeled "the girls in the test tube" - as in, they break out of those tubes and then tries to kill you - and they look like the zombie mooks. And at some point you get to see the corpse of the child-sized zombies lying all over the floor, only to see nothing shortly afterwards.
- In the Moon Shadow comic, we get a close-up of the nasty experiments performed in Schicksal's research labs; an A-rank Valkyrie gets the Gem of Serenity (the core of the Herrscher of Death) implanted into her body in order to test its compatibility. The experiment suddenly turns into a failure as the Valkyrie's body slowly and painfully disintegrates due to being unable to withstand the core's power. Her grandfather, one of Schicksal's scientists, can't do anything but watch her slowly die, while Otto coldly states the results of the experiment and nonchalantly tells the staff to clean up the mess.
- The fate of Jixuanyuan, a hero who sealed herself along with the Chiyou only to end up inside one hell of a Womb Level, alive, awake, aware and alone. By the time the hero trio get to meet her, her soul has completely eroded from the torment, forcing them to put her out of her misery, which she thanks them for as she dies.
- Thank goodness the "bubble universes" in the Sea of Quanta are basically simulations, because otherwise World 3 in Chapter 11 would be significantly more horrifying than it already is. When Welt turns on the Valkyries and starts a mass slaughter, things go south rapidly. When Mei attempts to take charge of the situation and tries to come up with a new plan, she's just suddenly obliterated, driving poor Kiana right into the Despair Event Horizon. While Bronya is trying to escape with Seele and Kiana, both of them disappear in quick succession, implying Welt's mechs killed them both as well (though Seele shows up alive later, Kiana has no such luck). By the time Bronya defeats Welt, it's implied that almost nobody out of both Schicksal and Anti-Entropy is left alive, and there are barely any surviving Valkyries.
- The trailer for the upcoming animation, "Reawakening", serving as the prelude to Fu Hua's Character Focus. The good news: Fu Hua has returned! The bad news: she's gone completely insane.
- Fu Hua defeats Bright Knight Durandal by turning dozens of the former's feathers into spears and destroying the latter's King phantom.
- Fu Hua no sells a direct hit from the Might of An-Utu and perches on it. You know things are bad when even Kevin is shocked.
- Fu Hua attacks Herrscher Bronya in a way that would make Berserker proud: by hijacking, riding, and crashing an anti-aircraft missile. Bronya shields herself from the blast in the ocean, only for Fu Hua to break through anyway with the most psychotic smile we've ever seen on her face, forcing Project Bunny 19C to sacrifice itself to save its owner.
- The final scene, where Kiana recognizes just who the source of the apocalyptic-looking maelstrom is in front of her.Kiana: You are...
Fu Hua: Can't recognize me anymore, Kiana? I will reverse all of creation.
- Murata Ryusuke's abrupt descent into villainy in the Alien Space comic confirms Uncle Konpeito's stance as to why the Sugars don't interfere with humanity and bemoaned Pepper Mint's naive belief as the latter hadn't seen the worst of humanity. It is also a somber reminder that it's a very nasty affair to argue with people who are obsessed with one idea and will fervently tear down your counter-arguments at every turn, then resort to violence when they feel there's no longer room for negotiation. In his increasingly hostile rant about wanting to revive Project ARK's space exploration despite Welt's realistic projections about humanity's limited resources, Ryusuke ignores Welt's pleas to think about Himeko's future and is convinced tthat Anti-Entropy is an enemy that's in the way of his ambitions, brutally taking Pepper Mint's power for himself in the process.Ryusuke: I'm ready to sacrifice anything for the sake of humanity's future! You're just like Schicksal. Myopic cowards who'll never lead the human race anywhere! You're a joke! If you refuse to take my offer... [Grabs Pepper Mint in his hand and crushes him] Then I will take just what I need...
- The moment when Fu Hua cold-bloodedly murdering Otto at the beginning of Chapter 20. In the first-person view. After Fu Hua freed herself from Otto's containment pod since the Battle of Schicksal (Chapter 8), three different Compelling Voices are trying to convince her that Otto is a wretched viper responsible for every mess that happened in Chapter 8 and 9. Those voices claim themselves as Fu Hua's Id, Ego, and Superego, respectively, which implies being Fu Hua's Literal Split Personality. With the help of her Id and Superego, Fu Hua managed to regain consciousness, killing Otto with extreme prejudice, and ransacking the entire Schicksal HQ. Then Durandal found Otto's corpse, presumably horrified of what happened after that. While this moment is undeniably cathartic for those who hate Otto since Chapter 8 and 9, seeing a stern but well-meaning class monitor turned into a ruthless individual is nothing short of horrifying and heartwrenching. Then again, Otto is a person who loves playing contingencies, even from the grave; as Theresa said to Bronya during a briefing in the next cutscene, he is not an easy person to bring to justice.